CANCELLATION OF DOPPLER FREQUENCY SHIFT
AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MA
Pagination or Media Count:
A circuit is described which is capable of canceling first-order Doppler frequency shifts. It has potentialities in the fields of communication, data transmission, and navigation systems for vehicles moving at high velocities. The circuit has the following features 1 Received and transmitted frequencies at each of the stations involved are different, thus preventing feedback from the transmitting to the receiving antenna at the stations. 2 Amplification of the signals is provided at a frequency which can be chosen to have a convenient value. This factor is important in the case of microwave systems, since high-gain microwave amplifiers are much more expensive than, and not as reliable as, IF amplifiers operating at frequencies in the 1 to 300 mc range. 3 The system is capable of continuous-wave operation and simultaneous transmission and reception at each of the communicating stations.
- Radiofrequency Wave Propagation